Adapter Coupling

ABSTRACT

A combination includes a plurality of segments attached to one another end to end around a central space. A channel is disposed between the sides of the segments. A sealing ring is positioned in the channels. A tube has a first end disposed within the central space. A first protrusion extends radially outwardly from the tube and limits the extent to which the tube can extend into the central space. The combination is configured such that an end of a pipe element may be axially inserted into the central space and fasteners can be tightened to draw the segments toward one another.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of and claims benefit of priority toU.S. patent application Ser. No. 15/387,894, filed Dec. 22, 2016, whichapplication is based upon and claims the benefit of priority to U.S.Provisional Application No. 62/271,395, filed Dec. 28, 2015, bothapplications being hereby incorporated by reference.

FIELD OF THE INVENTION

This invention relates to mechanical couplings for joining pipe elementsend to end, and in particular, for joining flanged pipe elements tonon-flanged pipe elements.

BACKGROUND

As taught in the prior art, connecting a non-flanged polymer pipeelement to a flanged pipe element of either polymer or metal, requiresthe use of a backing ring, usually made of metal, and a polymer buttflange adapter. To effect the connection, the backing ring is slippedover the free end of the non-flanged polymer pipe element and then thebutt flange adapter is coaxially aligned with and fused to the free endof the non-flanged pipe element in a butt joint. This creates a flangedfacing on the previously non-flanged polymer pipe element which is thenengaged, flange to flange, with the flanged pipe element. The backingring is then brought to bear on the flange of the butt flange adapterand bolts are used to attach the backing ring to the flange of theflanged pipe element, capturing and retaining the flange of the buttflange adapter to the flanged pipe element. For polymer to metal flangeengagement under low pressure applications the soft polymer flange ofthe butt flange adapter deforms upon contact with the metal flange ofthe flanged pipe element to form a fluid-tight seal. For higher pressureapplications a face seal may be used between the interfacing flanges toensure fluid tightness.

While effective, this prior art practice suffers various disadvantages.Multiple parts, namely, the butt flange adapter and the backing ring,must be supplied and assembled onto the non-flanged polymer pipeelement. A fusing operation is necessary to join the butt flange adapterto the non-flanged polymer pipe. This requires a fusing machine, whichrequires power or a heat source for operation. The fusing operationitself takes time and is affected by the weather when joints are to bemade in the field. For example, cold weather will slow the fusingprocess, and can stop it entirely if severe enough. There is clearly aneed for improved components and a method for joining non-flangedpolymer pipe elements to flanged pipe elements.

SUMMARY

The invention concerns a combination, wherein in an example embodimentthe combination comprises a plurality of segments attached to oneanother end to end by fasteners to form a loop around a central space.Each of the segments comprises a first side and a second side. A channelis disposed between the first and second sides of the plurality ofsegments. The channel extends circumferentially around and faces thecentral space. A flexible, resilient sealing ring is positioned in thechannel. The sealing ring comprises first and second lobes that eachextend radially inwardly to define first and second ring inner sealsurfaces, respectively. The example combination further comprises a tubecomprising a first end disposed within the central space. A firstprotrusion extends radially outwardly and is disposed proximate thesecond sides of the plurality of segments. The first protrusion limitsan extent to which the first end of the tube can extend axially into thecentral space. A second protrusion extends radially outwardly and isdisposed within the central space. The second protrusion is axiallydisposed between the first protrusion and the first end. The secondsides of the plurality of segments and the first lobe of the sealingring are both axially disposed between the first and second protrusions.The first lobe is axially disposed between the second protrusion and thesecond sides of the plurality of segments, and the second protrusionextends radially outwardly farther than an inner radial extent of thefirst lobe such that the second protrusion and first lobe help retainthe tube within the sealing ring. In the example embodiment a sealingsurface is disposed between the first and second protrusions on an outersurface of the tube. The combination is shaped and configured such thatan end of a first pipe element may be axially inserted into the centralspace. The combination is shaped and configured such that once the endof the first pipe element is properly inserted into the central space,the fasteners can be tightened so as to draw the plurality of segmentstoward one another and the central space and thereby cause (1) the firstring inner seal surface to sealingly engage the sealing surface of thetube, and (2) the second ring inner seal surface to sealingly engage asealing surface of the first pipe element.

In an example combination the second protrusion comprises a firstsurface that slopes radially inwardly as it progresses axially towardthe first end of the tube. The second ring inner seal surface has adiameter sized to receive the first pipe element upon insertion of thefirst pipe element into the central space. The plurality of segmentscomprises no more than two the segments by way of example, and thefasteners comprise two threaded fasteners.

In an example combination the second protrusion comprises a firstsurface that slopes radially inwardly as it progresses axially towardthe first end of the tube. Further by way of example the second ringinner seal surface has a diameter sized to receive the first pipeelement upon insertion of the first pipe element into the central space.Also by way of example the sealing ring has an outer surface engagedwith and supporting the plurality of segments in a preassembled state inspaced apart relation sufficient to allow the first pipe element to beinserted into the central space.

In an example combination a plurality of segments comprises no more thantwo the segments. Further by way of example the fasteners comprise twothreaded fasteners. In an example the first and second protrusions eachextend continuously around an entire circumference of the tube. Also byway of example the combination is shaped and configured to join thefirst pipe element with a second pipe element.

In an example combination according to the invention the first andsecond pipe elements comprise different types of pipe elements. Thecombination is an adapter coupling that is shaped and configured to jointhe different types of pipe elements to each other. By way of examplethe fasteners, and the sealing ring together define a preassembled pipecoupling. In an example embodiment the combination is a preassembledpipe coupling that includes the plurality of segments, the fasteners,the sealing ring, and the tube. By way of example the sealing ringcomprises a radially-inwardly projecting rib disposed between the firstand second lobes.

In an example embodiment the second protrusion extends radiallyoutwardly less far than an inner radial extent of the second sides ofthe plurality of segments prior to tightening of the fasteners such thatthere is a radial clearance between the second protrusion and the secondsides of the plurality of segments. In a further example the combinationis shaped and configured to join the first pipe element with a secondpipe element, and the combination is shaped and configured to beattached to the first pipe element before being attached to the secondpipe element.

In an example embodiment of a combination the first pipe elementcomprises a plain end pipe element.

By way of example the combination is shaped and configured to join thefirst pipe element with a second pipe element, and the second pipeelement comprises a flanged pipe element. In an example embodiment thetube and plurality of segments are shaped and configured to mount to theflanged pipe.

The invention further encompasses a method of using the combinationaccording to the invention. An example method comprises:

while the first end of the tube is disposed in the central space,axially inserting the end of the first pipe element into the centralspace; and

while the end of the first pipe element is inserted into the centralspace, tightening the fasteners, which draws the plurality of segmentstoward one another and the central space and thereby causes (1) thefirst ring inner seal surface to sealingly engage the sealing surface ofthe tube, and (2) the second ring inner seal surface to sealingly engagethe sealing surface of the first pipe element.

In an example method the tightening causes the second sides of thesegments to move radially inwardly past an outer radial extent of thesecond protrusion. A further example method of comprises attaching asecond pipe element to the tube so as to form a fluid-tight seal betweenthe second pipe element and the tube. In another example method theattaching occurs after the axially inserting and after the tightening.

The invention also encompasses a tube shaped and configured forengagement with a coupling. In an example embodiment the tube comprisesa plurality of segments attached to one another end to end by fastenersto form a loop around a central space. Each of the segments comprising afirst side and a second side, wherein a channel is disposed between thefirst and second sides of the plurality of segments, wherein the channelextends circumferentially around and faces the central space. Aflexible, resilient sealing ring is positioned in the channel. Thesealing ring comprises first and second lobes that extend radiallyinwardly to define first and second ring inner seal surfaces,respectively. By way of example the tube comprises a first endconfigured to be disposed within the central space when the tube isengaged with the coupling. A first protrusion extends radially outwardlyand is shaped and configured to be disposed proximate the second sidesof the plurality of segments when the tube is engaged with the coupling.The first protrusion is shaped and configured to limit an extent towhich the first end of the tube can extend axially into the centralspace. A second protrusion extends radially outwardly, and a sealingsurface is disposed between the first protrusion and second protrusionon an outer surface of the tube. The tube is shaped and configured suchthat when the tube is engaged with the coupling, (1) the secondprotrusion is within the central space, (2) the second sides of theplurality of segments and first lobe are both axially disposed betweenthe first and second protrusions, (3) the first lobe is axially disposedbetween the second protrusion and the second sides of the plurality ofsegments, (4) the second protrusion extends radially outwardly fartherthan an inner radial extent of the first lobe such that the secondprotrusion and first lobe help retain the tube within the sealing ring,(5) an end of a first pipe element may be axially inserted into thecentral space, and (6) the fasteners can be tightened so as to draw theplurality of segments toward one another and the central space andthereby cause the first ring inner seal surface to sealingly engage thesealing surface of the tube in this example embodiment.

In an example embodiment of a combination with the sealing ring, thefirst lobe is axially disposed between the first and second protrusions.The first end and second protrusions of the tube are disposed within acentral opening formed by the sealing ring. The second protrusionextends radially outwardly farther than an inner radial extent of thefirst lobe such that the second protrusion and first lobe help retainthe first end of the tube within the central opening.

In an example embodiment the tube is shaped and configured such thatwhen the tube is engaged with the coupling and the end of the first pipeelement is properly inserted into the central space, the fasteners canbe tightened so as to draw the plurality of segments toward one anotherand the central space and thereby cause (1) the first ring inner sealsurface to sealingly engage the sealing surface of the tube, and (2) thesecond ring inner seal surface to sealingly engage a sealing surface ofthe first pipe element.

In an example embodiment of the tube, the coupling is shaped andconfigured to join the first pipe element to a second pipe element. Inanother example embodiment, the tube is shaped and configured such thatwhen the tube is engaged with the coupling, the second protrusionextends radially outwardly less far than an inner radial extent of thesecond sides of the plurality of segments such that there is a radialclearance between the second protrusion and the second sides of theplurality of segments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric exploded view of an example coupling according tothe invention;

FIG. 1A is an isometric view of an example coupling according to theinvention shown in a preassembled state;

FIG. 2 is a longitudinal sectional view taken at line 2-2 of FIG. 1A;

FIG. 3 is a cross sectional view taken at line 3-3 of FIG. 2;

FIG. 3A is a cross sectional view taken at line 3A-3A of FIG. 2;

FIG. 4 is an isometric view of the coupling shown in FIG. 1 shownengaging a non-flanged pipe element;

FIG. 5 is a longitudinal sectional view showing the coupling of FIG. 1connecting a flanged pipe element to a non-flanged pipe element; and

FIG. 6 is an axial view of the coupling shown in FIG. 1.

DETAILED DESCRIPTION

FIG. 1 shows an example embodiment of a coupling 10 for joining flangedpipe elements to non-flanged pipe elements according to the invention.Coupling 10 comprises a plurality of segments, in this example, twosegments 12 and 14 attached to one another end to end and surrounding acentral space 16. Segments 12 and 14 are advantageously formed of castductile iron, although other materials may also be used. Attachment ofthe segments 12 and 14 is effected via adjustable attachment members 18positioned at each end of each segment. In this example attachmentmembers 18 comprise projections 20 that extend from the ends of thesegments, the projections having openings 22 that receive a fastener,such as bolt 24 and nut 26. Upon tightening of the fasteners 24, 26 thesegments 12 and 14 are drawn toward one another and the central space 16to effect connection with a pipe element 28 as shown in FIGS. 4 and 5and described below.

As shown in FIG. 2, coupling 10 has first and second sides 30 and 32oppositely disposed from one another. A first channel 34 is positionedin the segments 12 and 14 proximate to the first side 30. First channels34 extend circumferentially around and face the central space 16. Firstchannels 34 are each defined by two side surfaces 36 and 38 arranged inspaced apart relation to one another. A floor surface 40 extends betweenthe side surfaces. As shown in FIG. 3, the floor surface 40 comprisesfirst and second surface portions 42 and 44 arranged respectively atopposite ends 46 and 48 of the segments 12 and 14 (segment 12 beingshown). A third surface portion 50 is positioned between the first andsecond surface portions 42 and 44. Each surface portion 42, 44 and 50has a respective radius of curvature 42 a, 44 a and 50 a. Radii 42 a and44 a are greater than the radius of curvature 50 a of the third surfaceportion 50. The centers of radii 42 a and 44 a are offset from thecenter of radius 50 a as depicted in FIG. 3. The first and secondsurface portions 42 and 44 may each have a length extending from about5% to about 45% of the total length of the first channel 34 forpractical coupling designs.

As shown in FIGS. 1 and 2, coupling 10 further comprises a first flange52 positioned proximate to the second sides 32 of each segment 12 and14. Flange 52 is formed of flange portions 52 a and 52 b on respectivesegments 12 and 14 and extends outwardly away from the central space 16.Flange 52 has a plurality of through holes 54 (see also FIG. 1A). Theflange 52 and through holes 54 are designed to mate with the flange of aflanged end pipe element as described below. A second channel 56 ispositioned in each segment 12, 14 between the first channels 34 and thefirst flanges 52. Second channels 56 extend circumferentially around andface the central space 16. Similar to first channels 34, second channels56 are each defined by two side surfaces 57 and 59 arranged in spacedapart relation to one another as shown in FIG. 2. A floor surface 61extends between the side surfaces. As shown in FIG. 3A, the floorsurface 61 comprises first and second surface portions 63 and 65arranged respectively at opposite ends 46 and 48 of the segments 12 and14 (segment 12 being shown). A third surface portion 67 is positionedbetween the first and second surface portions 63 and 65. Each surfaceportion 63, 65 and 67 has a respective radius of curvature 63 a, 65 aand 67 a. Radii 63 a and 65 a are greater than the radius of curvature67 a of the third surface portion 67. The centers of radii 63 a and 65 aare offset from the center of radius 67 a as depicted in FIG. 3A. Thefirst and second surface portions 63 and 65 may each have a lengthextending from about 5% to about 45% of the total length of the secondchannel 56 for practical coupling designs.

As shown in FIGS. 1 and 2, a split ring 58 is positioned within thefirst channels 34 of segments 12 and 14. Split ring 58 in this examplecomprises a plurality of teeth 60 arranged in spaced relation to oneanother. Teeth 60 extend circumferentially around the split ring 58 andproject toward the central space 16. Such split rings are made of metal,such as spring steel, stainless steel or copper-beryllium alloys and areeffective at retaining pipe elements made of HDPE or other polymerresins, to the coupling 10. The split ring 58 has an inner diameter 62equal to or greater than the outer diameter of the pipe element. Teeth60 may furthermore be angularly oriented to permit insertion of the pipeelement into central space 16, but prevent its withdrawal.

Split ring 58 may be used to hold the segments 12 and 14 in spaced apartrelation in the so-called “preassembled state”, illustrated in FIG. 1A.Split ring 58 has an outer diameter 64 sized to engage the first andsecond surface portions 42 and 44 of floor surface 40 (see FIG. 3).These surface potions have radii of curvature 42 a and 44 a larger thanthe third surface portion 50 and are designed to cooperate with thesplit ring 58 for support of the segments 12 and 14 such that the pipeelement 28 may be inserted into the central space 16 from side 30 whencoupling 10 is in the preassembled state. Fasteners (bolts 24 and nuts26) hold the segments 12 and 14 together and against the split ring 58,which has sufficient stiffness to support the segments during handlingfor installation but, being a split ring, is collapsible to a smallerdiameter and permits the segments to be drawn toward one another andeffect a fluid tight, mechanically restrained joint when the fastenersare tightened as described below.

Fluid tightness of the joint is afforded by a seal 66 positioned in thesecond channels 56 of segments 12 and 14 as shown in FIG. 2. In thisexample seal 66 comprises a flexible, resilient sealing ring 68. Sealingring 68 has an outer surface 70 having a diameter 71. In an exampleembodiment, diameter 71 is sized either to support the segments 12 and14 in spaced relation in the preassembled state, or to assist split ring58 in supporting the segments. To this end outer diameter 71 is sized toengage the first and second surface portions 63 and 65 of floor surface61 of the second channel 56 (see FIG. 3A). These surface portions haveradii of curvature 63 a and 65 a larger than the third surface portion67 and are designed to cooperate with the sealing ring 68 for support ofthe segments 12 and 14 to permit insertion of the pipe element 28 intothe central space 16 from side 30 when coupling 10 is in thepreassembled state shown in FIG. 1A. Sealing ring 68 may also havesufficient stiffness to support the segments during handling forinstallation. Sealing ring 68 may be formed of elastomers such as EPDMand is thus deformable upon tightening of the fasteners 24, 26 to permita joint to be formed as described below.

To effect a fluid tight seal, sealing ring 68 has first and second ringinner surfaces 72 and 74 positioned on opposite sides of the sealingring. Surface 72 is positioned and adapted to engage the outer surfaceof pipe element 28 upon insertion of the pipe element into the centralspace 16 (described below). As shown in FIG. 2, surface 74 is adapted toengage the outer surface of a tube 76 positioned within the centralspace 16. A barb 77 is positioned proximate one end of tube 76 to engagethe lobe 74 a on which inner surface 74 is positioned. Barb 77 extendscircumferentially around and outwardly from tube 76 and helps retain thetube within sealing ring 68. Tube 76 is part of the coupling 10 andextends outwardly from the second sides 32 of the segments 12 and 14. Asecond flange 78 may extend outwardly from tube 76 and is positioned inspaced relation away from barb 77, adjacent to the first flange 52 whenthe opposite end of the tube 76 is engaged by the inner surface 74 ofsealing ring 68 as illustrated in FIG. 2. It is advantageous to formtube 76 and its flange 78 as a unitary piece from a polymer resin suchas HDPE. This design helps ensure fluid tightness of the joint as notedbelow. Sealing ring 68 may also have an inwardly projecting rib 80 thatengages both the tube 76 and the pipe element 28 and acts as a stop toensure proper depth of engagement between these components and thecoupling 10.

Installation of the coupling 10 is illustrated with reference to FIGS.1A, 4, 5 and 6. Pipe element 28 is to be connected to a flanged pipeelement 82 (see FIG. 5). As shown in FIGS. 1A and 6, the pipe element 28is inserted into the central space 16 of coupling 10 from the first side30 of the segments 12 and 14. Insertion is possible because the coupling10 is in the preassembled state, with segments 12 and 14 supported inspaced relation either on seal 66 alone, split ring 58 alone, or on boththe seal and the split ring. Insertion is further aided by notches 94positioned in side surfaces 36, 38 of each segment 12 and 14. Thenotches 94 are positioned adjacent to the attachment members 18(projections 20) and provide clearance for pipe element insertion whichpermits the segments 12 and 14 to be closer together in the preassembledstate than would be possible in the absence of the notches. Once pipeelement 28 is properly seated (the end engaging stop rib 80, the sealingring inner surface 72 engaging the outer surface of the pipe element)fasteners 24, 26 are tightened thereby drawing segments 12 and 14 towardone another as shown in FIGS. 4 and 5. Motion of the segments 12 and 14deforms both the split ring 58 and the seal 66.

Split ring 58 shrinks in circumference and diameter as it is forced toconform within the first channel 34. Shrinking of split ring 58 causesteeth 60 on the split ring to bite into the outer surface of the pipeelement 28 and prevent its withdrawal from the coupling 10. Seal 66,constrained within the second channel 56, is compressed between thesegments 12 and 14 as the segments are brought together. As shown inFIG. 5, the sealing ring inner surface 72 is forced into sealingengagement with the outer surface 84 of the pipe element 28, and sealingring inner surface 74 is brought into sealing engagement with the outersurface 86 of tube 76.

With the segments 12 and 14 brought together as depicted in FIGS. 4 and5, the first flange 52 is thus arranged so that its holes 54 may bealigned with corresponding holes 88 in the flange 90 of the flanged pipeelement 82 to which the pipe element 28 is to be joined. As shown inFIG. 5, the coupling 10 is aligned with the flanged pipe element 82,holes 54 in the first flange 52 are aligned with holes 88 in flange 90and fasteners 92 are received in holes 54 and 88 to connect the firstflange 52 to the flange 90 of the flanged pipe element 82. Second flange78 of tube 76 is captured between flange 90 and first flange 52. Thisconfiguration provides stiffness and stability to the joint as well asfluid tightness between the coupling 10 and the flanged pipe element 82as the softer polymeric material comprising the second flange 78 iscompressed between the metal flanges 90 and 52, which may comprise castiron, steel or other durable metals.

Couplings according to the invention provide advantages over prior artmethods and couplings for joining non-flanged polymeric pipe elements toflanged pipe elements. Being in a pre-assembled state, couplingsaccording to the invention reduce the number of parts that must behandled during installation. Furthermore, the step of fusing a buttflange adapter to the non-flanged polymer pipe element is eliminatedalong with the need for a fusing machine. Installation time andcomplexity is thereby reduced substantially.

What is claimed is:
 1. A combination, comprising: a plurality ofsegments attached to one another end to end by fasteners to form a looparound a central space, each of said segments comprising a first sideand a second side, wherein a channel is disposed between the first andsecond sides of the plurality of segments, wherein the channel extendscircumferentially around and faces said central space; a flexible,resilient sealing ring positioned in said channel, the sealing ringcomprising first and second lobes that each extend radially inwardly todefine first and second ring inner seal surfaces, respectively; and atube comprising a first end disposed within the central space, a firstprotrusion extending radially outwardly and disposed proximate thesecond sides of the plurality of segments, wherein the first protrusionlimits an extent to which the first end of the tube can extend axiallyinto the central space, a second protrusion extending radially outwardlyand disposed within the central space, wherein the second protrusion isaxially disposed between the first protrusion and the first end, whereinthe second sides of the plurality of segments and the first lobe of thesealing ring are both axially disposed between the first and secondprotrusions, wherein the first lobe is axially disposed between thesecond protrusion and the second sides of the plurality of segments, andthe second protrusion extends radially outwardly farther than an innerradial extent of the first lobe such that the second protrusion andfirst lobe help retain the tube within the sealing ring, and a sealingsurface disposed between the first and second protrusions on an outersurface of the tube, wherein the combination is shaped and configuredsuch that an end of a first pipe element may be axially inserted intothe central space, and wherein the combination is shaped and configuredsuch that once the end of the first pipe element is properly insertedinto the central space, the fasteners can be tightened so as to draw theplurality of segments toward one another and the central space andthereby cause (1) the first ring inner seal surface to sealingly engagethe sealing surface of the tube, and (2) the second ring inner sealsurface to sealingly engage a sealing surface of the first pipe element.2. The combination of claim 1, wherein: the second protrusion comprisesa first surface that slopes radially inwardly as it progresses axiallytoward the first end of the tube; the second ring inner seal surface hasa diameter sized to receive said first pipe element upon insertion ofsaid first pipe element into the central space; said plurality ofsegments comprises no more than two said segments; and the fastenerscomprise two threaded fasteners.
 3. The combination of claim 1, whereinthe second protrusion comprises a first surface that slopes radiallyinwardly as it progresses axially toward the first end of the tube. 4.The combination of claim 1, wherein the second ring inner seal surfacehas a diameter sized to receive said first pipe element upon insertionof said first pipe element into the central space.
 5. The combination ofclaim 4, wherein said sealing ring has an outer surface engaged with andsupporting said plurality of segments in a preassembled state in spacedapart relation sufficient to allow said first pipe element to beinserted into said central space.
 6. The combination of claim 1, whereinsaid plurality of segments comprises no more than two said segments. 7.The combination of claim 6, wherein the fasteners comprise two threadedfasteners.
 8. The combination of claim 1, wherein first and secondprotrusions each extend continuously around an entire circumference ofthe tube.
 9. The combination of claim 1, wherein the combination isshaped and configured to join the first pipe element with a second pipeelement.
 10. The combination of claim 9, wherein the first and secondpipe elements comprise different types of pipe elements, and wherein thecombination is an adapter coupling that is shaped and configured to jointhe different types of pipe elements to each other.
 11. The combinationof claim 1, wherein the plurality of segments, the fasteners, and thesealing ring together define a preassembled pipe coupling.
 12. Thecombination of claim 11, wherein the combination is a preassembled pipecoupling that includes the plurality of segments, the fasteners, thesealing ring, and the tube.
 13. The combination of claim 1, wherein thesealing ring comprises a radially-inwardly projecting rib disposedbetween the first and second lobes.
 14. The combination of claim 1,wherein the second protrusion extends radially outwardly less far thanan inner radial extent of the second sides of the plurality of segmentsprior to tightening of the fasteners such that there is a radialclearance between the second protrusion and the second sides of theplurality of segments.
 15. The combination of claim 1, wherein: thecombination is shaped and configured to join the first pipe element witha second pipe element; and the combination is shaped and configured tobe attached to the first pipe element before being attached to thesecond pipe element.
 16. The combination of claim 1, wherein the firstpipe element comprises a plain end pipe element.
 17. The combination ofclaim 1, wherein: the combination is shaped and configured to join thefirst pipe element with a second pipe element; and the second pipeelement comprises a flanged pipe element.
 18. The combination of claim17, wherein the tube and plurality of segments are shaped and configuredto mount to the flanged pipe.
 19. A method of using the combination inclaim 1, the method comprising: while the first end of said tube isdisposed in said central space, axially inserting the end of the firstpipe element into the central space; and while the end of the first pipeelement is inserted into the central space, tightening the fasteners,which draws the plurality of segments toward one another and the centralspace and thereby causes (1) the first ring inner seal surface tosealingly engage the sealing surface of the tube, and (2) the secondring inner seal surface to sealingly engage the sealing surface of thefirst pipe element.
 20. The method of claim 19, wherein said tighteningcauses the second sides of the segments to move radially inwardly pastan outer radial extent of the second protrusion.
 21. The method of claim19, further comprising attaching a second pipe element to the tube so asto form a fluid-tight seal between the second pipe element and the tube.22. The method of claim 21, wherein said attaching occurs after saidaxially inserting and after said tightening.
 23. A tube shaped andconfigured for engagement with a coupling that comprises: a plurality ofsegments attached to one another end to end by fasteners to form a looparound a central space, each of said segments comprising a first sideand a second side, wherein a channel is disposed between the first andsecond sides of the plurality of segments, wherein the channel extendscircumferentially around and faces said central space; and a flexible,resilient sealing ring positioned in said channel, the sealing ringcomprising first and second lobes that extend radially inwardly todefine first and second ring inner seal surfaces, respectively, the tubecomprising: a first end configured to be disposed within the centralspace when the tube is engaged with the coupling, a first protrusionextending radially outwardly and shaped and configured to be disposedproximate the second sides of the plurality of segments when the tube isengaged with the coupling, wherein the first protrusion is shaped andconfigured to limit an extent to which the first end of the tube canextend axially into the central space, a second protrusion extendingradially outwardly, and a sealing surface disposed between the firstprotrusion and second protrusion on an outer surface of the tube,wherein the tube is shaped and configured such that when the tube isengaged with the coupling, (1) the second protrusion is within thecentral space, (2) the second sides of the plurality of segments andfirst lobe are both axially disposed between the first and secondprotrusions, (3) the first lobe is axially disposed between the secondprotrusion and the second sides of the plurality of segments, (4) thesecond protrusion extends radially outwardly farther than an innerradial extent of the first lobe such that the second protrusion andfirst lobe help retain the tube within the sealing ring, (5) an end of afirst pipe element may be axially inserted into the central space, and(6) the fasteners can be tightened so as to draw the plurality ofsegments toward one another and the central space and thereby cause thefirst ring inner seal surface to sealingly engage the sealing surface ofthe tube.
 24. The tube of claim 23, in combination with the sealingring, wherein: the first lobe is axially disposed between the first andsecond protrusions, the first end and second protrusion of the tube aredisposed within a central opening formed by the sealing ring, and thesecond protrusion extends radially outwardly farther than an innerradial extent of the first lobe such that the second protrusion andfirst lobe help retain the first end of the tube within the centralopening.
 25. The tube of claim 24, wherein the tube is shaped andconfigured such that when the tube is engaged with the coupling and theend of the first pipe element is properly inserted into the centralspace, the fasteners can be tightened so as to draw the plurality ofsegments toward one another and the central space and thereby cause (1)the first ring inner seal surface to sealingly engage the sealingsurface of the tube, and (2) the second ring inner seal surface tosealingly engage a sealing surface of the first pipe element.
 26. Thetube of claim 23, wherein the coupling is shaped and configured to jointhe first pipe element to a second pipe element.
 27. The tube of claim23, wherein, the tube is shaped and configured such that when the tubeis engaged with the coupling, the second protrusion extends radiallyoutwardly less far than an inner radial extent of the second sides ofthe plurality of segments such that there is a radial clearance betweenthe second protrusion and the second sides of the plurality of segments.